Disperse systems: kev coj tus yam ntxwv thiab kev faib tawm

Colloid chemistry yog ib qho kev tshawb fawb uas kawm txog txoj kev npaj, muaj pes tsawg leeg, kev ua haujlwm sab hauv, tshuaj lom neeg thiab lub cev ntawm kev sib faib tshuab. Disperse systems yog systems uas muaj fragmented particles (dispersed phase) faib rau hauv nruab nrab (disperse) nruab nrab: gases, liquids, or solids. Qhov loj me me ntawm cov theem dispersion (cov nplais, qhov mob, npuas) sib txawv hauv cov degree ntawm dispersion, qhov ntau ntawm cov uas ncaj ncaj ncaj ncees rau qhov luaj li cas ntawm cov khoom. Nyob rau hauv tas li ntawd, particulate teeb meem yog distinguished, thiab nyob rau lwm thaj chaw, raws li ib tug txoj cai, lub xeev ntawm aggregation ntawm lub dispersed theem thiab qhov ib puag ncig.

Disperse systems thiab lawv cov kev faib tawm

Tag nrho cov txheej txheem dispersion tuaj yeem muab cais tawm raws li qhov loj ntawm cov zauv ntawm cov dispersion theem rau molecular-ion (tsawg dua ib nm), colloidal (los ntawm ib rau ib puas nm), coarsely dispersed (ntau tshaj ib puas npaug nm).

Molecular dispersed systems. Cov tshuab no muaj cov ntsiab lus uas nws loj npaum li cas tsis tshaj ib tus nm. Cov pab pawg no muaj ntau yam ntsiab lus tseeb ntawm nonelectrolytes: piam thaj, kua, cawv, sucrose.

Lub tshem tawm tshuab yog yus muaj los ntawm cov loj tshaj plaws hais. Cov no muaj xws li emulsions thiab kev ncua. Disperse systems nyob rau hauv uas lub khoom yog laus nyob rau hauv ib cov kua dispersion nruab nrab (cov hmoov txhuv nplej tshuaj, av nplaum) raug xa mus rau raws li ncua. Emulsions yog cov tshuab tau los ntawm sib tov ob kua, ib qho nyob rau hauv daim ntawv ntawm cov kua dej tau muab faib rau lwm tus (roj, toluene, benzene hauv dej los yog mob ntawm triacylglycerols (rog) hauv mis.

Colloidal dispersions. Nyob rau hauv lawv, qhov ntau thiab tsawg ntawm colloidal hais txog li 100 nm. Xws li hais yooj yim nkag mus rau cov pores ntawm cov ntxaij lim dej, tab sis tsis txeem lub qhov hws ntawm cov roj ntsha ntawm cov nroj tsuag thiab cov tsiaj. Vim colloidal particles (micelles) muaj hluav taws xob nqi thiab txhim kho ionic shells, vim lawv nyob hauv ib lub xeev raug ncua, lawv tuaj yeem tsis precipitate ntev. Ib tug piv txwv ntawm colloidal systems yog kev daws teeb meem ntawm gelatin, albumin, cov pos hniav Arabic, colloidal kev daws teeb meem ntawm cov nyiaj thiab kub.

Cov degree ntawm dispersity ua kom tau qhov txawv ntawm homogeneous thiab heterogeneous disperse systems. Hauv homogeneous disperse systems, cov theem ntawm cov av muaj cov hauv pem teb rau molecules, atoms thiab ions. Ib qho piv txwv ntawm cov dispersion hauv lub nruab yuav ua tau los ntawm cov dej qab zib (molecular dispersion system) thiab chav ua noj hauv dej (ion-dispersed system). Lawv yog cov ntsiab lus tseeb. Qhov luaj li cas ntawm cov txheej txheem ntawm tus txheejtxheem tsis pub tshaj ib nanometer.

Disperse systems thiab cov kev daws teeb meem

Ntawm tag nrho cov qauv thiab cov qauv sawv cev hauv lub neej ntawm cov kab mob nyob hauv, qhov tseem ceeb tshaj plaws yog colloidal disperse systems. Raws li yog lub npe hu, cov tshuaj lub hauv paus rau lub hav zoov ntawm ib tug nyob kab mob yog lub metabolism ntawm cov nqaijrog nyob rau hauv nws. Qhov nruab nrab, qhov concentration ntawm cov nqaijrog hauv lub cev yog los ntawm 18 mus rau 21%. Feem ntau cov proteins uas yaj nyob hauv dej (qhov concentration ntawm cov tib neeg lub cev thiab cov tsiaj yog kwv yees li 65%) thiab daim ntawv colloidal daws.

Muaj ob pawg kev sib txuas ntawm colloidal: kua (kua roj ntsha) thiab gel zoo li (gels). Tag nrho cov kev ua hauv lub neej uas tshwm sim hauv cov kab tsuag tsiaj muaj feem xyuam nrog lub colloidal xeev ntawm qhov teeb meem. Hauv txhua lub cell, biopolymers (nucleic acids, proteins, glycosaminoglycans, glycogen) yog nyob rau hauv daim ntawv ntawm disperse systems.

Colloidal kev daws teeb meem yog ntau thiab inorganic xwm. Tej kev daws teeb meem muaj xws li roj, fabrics, yas, hluavtaws fibers. Muaj ntau hom zaub mov tuaj yeem yog vim muaj cov ntsiab lus colloidal: kefir, mis, thiab lwm yam. Feem ntau cov tshuaj (serums, antigens, tshuaj txhaj tiv thaiv) yog colloidal daws. Rau qhov cov ntsiab lus colloidal muaj xim.